The candidate proposes to purify the nuclear thyroid hormone receptor from rat liver and obtain its partial amino acid sequence. Methods are currently available for its partial purification, and the candidate will both develop new methods to further purify the receptor and to optimize current procedures. Purified receptor will be sequenced in one hundred picomolar quantities. These sequences will enable the candidate to engage in further studies which include preparing antibodies to the receptor or synthesizing a cDNA primer. Thus, new information about the thyroid hormone receptor will be obtained which can be used to elucidate the mechanism of action of thyroid hormone. The candidate's previous experience in adrenergic binding mechanisms and in membrane protein purification serves as an excellent background for these studies. This proposal has two immediate goals. The first is to strengthen the biochemical skills of the candidate. The second is to allow the candidate to work in an environment where recombinant DNA technology can be learned and to provide a straightforward framework from which to practice this methodology. Thus, partial amino acid sequence information can be used to generate cDNA probes which will allow receptor mRNA to be identified.